Top-5 Factors Causing Deer Population Declines

Hunters throughout the whitetail’s range are complaining of declining deer populations. Not all hunters, of course, but enough to draw newspaper headlines, DNR deer management plan audits, and legislation aimed at growing deer herds. Are these declines real, and if so, what are the driving factors?

We can look at current antlered buck harvests and compare them to buck harvests a decade ago to monitor the presence and degree of changes in herd size. Changes in buck harvest can be a good index to changes in the actual herd size, and they are a great index to hunters’ perceptions of the actual herd size. A state-by-state analysis would be much longer than this article allows, so I’ll assess it on a regional basis and divide the U.S. into the Midwest, Northeast and Southeast regions. (You can review the state-by-state information in our 2015 Whitetail Report).

The 2013-14 deer season is the most recent data available for use in comparing all states, so I’ll use data from that season and compare it to 10 years prior in the 2003-04 season. Deer populations were at all-time highs in many states a decade ago, so this analysis can compare current hunting opportunities with those often considered “the good ole days.”

Antlered Buck Harvest by Region

The Southeast shot nearly identical numbers of bucks in 2003 and 2013. The difference was only 17,794 bucks (1 percent). The Northeast also shot nearly identical numbers in 2003 and 2013 with a difference of only 18,011 bucks (3 percent). Amazingly, these regions shot nearly equal numbers of bucks, but the age structure was vastly improved in 2013.

In 2003, yearling bucks constituted nearly 50 percent of all bucks harvested, and bucks 3½ years and older only accounted for just over 20 percent. However, by 2013 those numbers were nearly equal at 36 and 34 percent, respectively! Think about that for a minute. These two regions are shooting approximately the same number of bucks today as in 2003 but are shooting many more that are 2½, 3½, 4½ and 5½ years old. Wow, that sounds pretty good to me.

The Midwest however is a very different story, as the buck harvest declined by more than 125,000 bucks from 2003 to 2013. It was the first time since at least 2009 the buck harvest in this region dropped below 1 million bucks.

I believe there are five main reasons for the declines experienced in several Midwestern states.

1 – Hemorrhagic Disease

We had a record hemorrhagic disease (HD) outbreak in 2007 and another in 2012. The Midwest lost tens of thousands of deer to HD and many states haven’t fully recovered from it.

2 – Severe Winter Weather

We experienced severe winter weather during the past few years. Severe winters in the Upper Midwest can increase adult mortality, reduce fawn survival, and impact antler growth the following year as bucks have to recover the additional weight lost during the severe winter. This leaves less nutrition for antler growth.

3 – Intentional Herd Reduction

Several states were intentionally reducing their deer herds over the past decade. Many states were aggressively harvesting antlerless deer, and when you reduce the herd the buck harvest declines. In the Midwest today, only one state wildlife agency (Indiana) says it is trying to reduce the deer herd, the others are either trying to stabilize or grow their herds.

4 – Falling Fawn Recruitment

Eight states in the Midwest measure fawn recruitment rates today. In my opinion, every state should be monitoring this important statistic. Back in 2005 only five of the eight states measured fawn survival, and it has dropped in all five from 2005 to 2014. You can blame it on predators, nutrition, climate change, or whatever you’d like, but the reality is far fewer fawns are surviving today than they did a decade ago. Approximately every other fawn born is a buck fawn, so fewer fawns means fewer bucks are recruited into the herd.

5 – Habitat Loss

The last reason is arguably the most important in this list, and it is habitat loss. From 2007 to 2014 the U.S. enrolled 9.1 million fewer acres into the USDA’s Conservation Reserve Program (CRP). The CRP is the most successful federal wildlife habitat program, and it pays landowners a fee to convert highly erodible cropland and environmentally sensitive acreage to wildlife habitat. It can include grasses, trees, windbreaks, shelterbelts, buffer strips and more. In most cases, CRP acres provide exceptional wildlife habitat, and this is especially true in the intensively row-cropped Midwest where cover was already the limiting habitat component. As a whole, the United States lost over 25 percent of its CRP acreage from 2007 to 2014 as the land was put back into agricultural production, largely as a result of record high corn and soybean prices, and the Midwest alone lost over 5 million acres of CRP! North Dakota lost over 1.5 million acres, and Kansas lost over 700,000 acres. The table shows how each state fared, but every state in the Midwest lost acreage.

The Northeast lost 17 percent of its CRP and the Southeast lost 20 percent. However, cover is not as critical a limiting factor in these regions as it is the Midwest, so the impact on deer populations is less noticeable.

What Does All This Mean for Hunters?

Overall things are pretty good for hunters in the Northeast and Southeast. This doesn’t mean all hunters in these regions are having their best years of all time. Rather it means as a whole the regions are doing well. State wildlife agencies collect data at the wildlife management unit level while we hunt at the property level. There can be a big difference between those, so we shouldn’t assume all other hunters’ experiences are similar to ours.

While things may be good in the Northeast and Southeast, it’s a very different story in much of the Midwest. I say “much of” because some states like Kansas have more deer today than a decade ago and others like Kentucky are shooting a lot more bucks today than a decade ago. However, most Midwestern states are dealing with changes in their deer herds and habitats, and this results in disgruntled hunters. Deer management is in a very different place today than a decade ago. As deer herd size has changed, so have harvest goals, and many hunters are frustrated by this. Unlike short-term impacts of HD and severe winter, major habitat loss in the Midwest will plague deer herds for years to come.

  • Brad

    In SC, the doe harvest, over the past 20 plus years, has been an all out slaughter. Now hunters in most areas are wondering why they aren’t seeing deer?

    Coyote populations have increased as well as loss of habitat. However, the trigger finger is by far the greatest reason for the decline.

    Maybe more hunters should get familar with Aldo Leupold and how hard conservation agency’s worked to save rebuild populations of wildlife.

    • Kip Adams

      Brad – trigger finger management is a big part of any deer management program, and that’s why we help hunters determine the appropriate number of antlerless deer to shoot each year in their area. Sometimes it is a lot and some times it is none. Good luck in the woods this year.

  • rreno1

    I can’t believe roundup spray and GMO seeds are not on this list, we saw a big decline about 5 years after we started to us RR seeds and spray in all wildlife on our farm, we even increase crp and trees but numbers still went down(we do active predator control and have a good clean water source/s). But then 2 of us on the farm got cancer from spraying and we decided to go organic with everything(we both beat cancer). And after just 3 years we saw on camera a big jump in fawns and the does survived longer, and the quality of bucks went up as well. We have over 1200acres into crp/trees/sloughs and 400 into crop land and i swear by what we have seen, then plus we read a article on the effects of round spray and gmo seeds on reproduction of deer and we can verify that those scientific test were correct. People need to wake up on t his huge problem.

    • Kip Adams

      rreno1 – first of all congratulations on beating cancer! Secondly, congrats on the success of your wildlife program. I’ve read several articles suggesting gmo seeds and glyphosate were negatively impacting deer, but none were scientific studies. I haven’t seen a scientific study have those same results. If you have one please let me know where to get a copy as I’d like to read it. Thanks and good luck in the woods this year.

      • rreno1

        Hi, the North American Whitetail Mag had a excellent scientific based article about this and its very clear with the description on how the science was achieved.

        • Kip Adams

          Thanks rreno1. I’ve read some of Dr. Hoy’s articles too, but none are scientific studies. I am not disagreeing with your suggestions. I am simply stating there’s not a scientific study that I am aware of that agrees with the information in the article.

          • rreno1

            I just find it odd that the number of deer started to go do the same time roundup spray and gmo came around, after we switched our crops back to orgainic and no gmo, why did we see a increase in healthy deer numbers and quality? Go over 3 sections from our farm and you be lucky to see 4-5 deer on a given morning. They use roundup and gmo. Plus this article is pretty scientific on how GP chealetes in the body and how it affects the reproductive system. I have seen 3 studies that say roundup don’t hurt wildlife, but when you dig deep into who funded them, it comes up a sister company of Monsanto. what are the odds. Plus we notice not a sign deer eats the soybeans of our neighbors 3 miles away that is right next to good cover, but they sure love our bean leaves. We will stick to what is working for us, and the rest of the hunting community will keep spinning their wheels to figure out what is happening.

          • Kip Adams

            rreno1 – your deer numbers may have started dropping at the same time as GMO seeds were used in your area, but that doesn’t mean the seeds or herbicide were harming the deer. GMO fields tend to be very clean and that’s generally not good for deer. I much prefer my crops to be a little weedy as deer and numerous other wildlife species benefit from those weeds. They are largely gone from GMO fields. Commercial ag folks don’t like weeds as they reduce their profits, but from a wildlife perspective, some weeds can be very good.

          • rreno1

            Well put it this way, the deciding factor/s to switch back to organic besides our reasons was when we noticed the hooves on the deer were really goofy and does dying at the age of 3 on a regular basis, you may choose to look the other way because roundup spray is convenient for food plots and such, but when a chemical starts to mess with the chelation of the minerals of the body then you will have major issues with the health. And we rather let mother nature take its course the right way. Plus chemical run off is hurting our drinking water supply in SD, big sioux river was deemed unsafe to even swim in all summer 6x’s the safe levels of nitrates, 4x’s the safe level of chemical/s . The james river was very close to the same levels as well. This study was done by the dnr and SDSU and epa. All linked to roundup sprays and farm run off of drain tiles. I understand no one wants to talk about the elephant in the room(roundup and gmo) but we saw the righting on the wall and our farm is proof of it.

  • T. Saroch

    Here in the south(Texas) I believe all the windmills have scattered the deer. A few years back, I could see deer like clockwork, they were in the same area day after day. Now we may see them one time and never again. I have been hunting this same ranch for 30 years. Last year we saw some opening day, and never again. To much noise and activity. That’s my opinion.

    • T. Saroch – windmills can be like gas and oil wells. Generally it’s not the actual structure that impacts deer sightings, but all of the human activity around it that’s associated with its use, maintenance, etc.

  • RJR

    I hear a lot from colleagues up north in Wisconsin, Michigan, Minnesota, etc that the growing wolf and bear population is wreaking havoc on their herds, particularly the fawns.

    • RJR – wolves and bears can certainly eat a lot of venison. Bears mainly prey on fawns while wolves routinely kill adult deer.

  • Jim

    Shooting too many Deer is the #1 reason, especially does.

    • Jim – you’re correct that shooting too many does is the main reason in some areas. In others, doe harvest has been light but habitat loss, disease loss and predation have greatly increased.

About Kip Adams

Kip Adams of Knoxville, Pennsylvania, is a certified wildlife biologist and QDMA’s Director of Conservation. He has a bachelor’s degree in wildlife and fisheries science from Penn State University and a master’s in wildlife from the University of New Hampshire. He’s also a certified taxidermist. Before joining QDMA, Kip was the deer and bear biologist for the New Hampshire Fish & Game Department. Kip and his wife Amy have a daughter, Katie, and a son, Bo.